A review of the superheavy load permitting programme in Texas

Regulating and permitting superheavy loads is a part of the Department of Transportation's operation. Since the size and weight of the superheavy loads greatly exceeds that of ordinary trucks, pavement engineers face a challenge if they do not have an appropriate analysis procedure. This paper covers the general superheavy load programme in Texas as well as some analysis and field monitoring done between November 2001 and November 2002. The results presented here are those related to gross vehicle weight (GVWs) greater than 227,000 kg where pavement analysis is required. There have been 63 superheavy load moves evaluated during the year monitored. There were three superheavy load moves of over 454,000 kg on load-zoned roads (with a GVW restriction of 26,520 kg). No structure-related damages or rapid shear failure have been observed during the monitoring period. Only three cases of minor pavement damage were reported by the districts as a result of superheavy moves. Two cases were related to a fresh seal coat overlay. Thus, superheavy load moves on such newly overlaid pavements should be curtailed in the future. Because of this observation, a policy was adopted to re-route superheavy load moves to 5 weeks or older pavements. Currently, it is thought that the structure is adequate to support the moves when the remaining life prediction from the Asphalt Institute equation is 585 repetitions or greater. Although there are imperfections in the analysis procedure adopted, Texas Department of Transportation (TxDOT) is committed to continuously improve the superheavy load analysis procedure with more on-site monitoring.